@inbook{Wagner1999,
author = {Wagner, M. and Schütze, Y. and Lang, F.R.},
title= {Social relationships in old age},
year = {1999},
editor = {Baltes, P.B.},
editor = {Mayer, K.U.},
booktitle = {The Berling Aging Study. Aging from 70 to 100},
address = {Cambridge},
publisher = {Cambridge University Press},
pages = {282--301},
}